Modern electric traction vehicles require large quantities of cooling air to cool the electric and electronic apparatus installed on the traction vehicle and to cool the traction motors. This cooling air is drawn in via ventilation grilles or louvres by means of axial or radial fans. After flowing through the various coolers or the traction motors, the heated air escapes again into the open.
The intake routes must be designed in such a way that entrained dust, snow and rain are largely separated outside the components to be cooled. Previously customary separators require either large intake areas (e.g. grilles having mat filters) and periodic maintenance or else considerable space (e.g. acceleration filters) plus the installation of additional scavenging devices.
With ventilation grilles of specific construction, as described, for example, in the book by Sachs "Elektrische Triebfahrzeuge", 2nd edition, volume 1, published by Springer, Vienna/New York 1973, pages 721-728, the current requirements can no longer be fulfilled in certain cases.
A method of increasing the separating efficiency is described in Austrian Patent Specification No. 375,843. This reference discloses a centrifugal separator for separating dust, snow and drops of water from the cooling air for an electrical machine, consisting of a cylindrical housing, an airflow duct body and a collecting vessel, annular in cross-section and fixed to the cylindrical housing, for dust, snow and drops of water. Provided in the cylindrical housing is an axial counterflow blower consisting of two contra-rotating fans; provided on the air discharge side of the counterflow blower is an axial airflow-passage body which on the one side, at the air discharge side of the counterflow blower, has guide vanes, which are curved in a radially threedimensional manner, are fixed in the cylindrical housing and deflect the airflow spirally around the airflow-passage body, and on the other side, at its end, has guide vanes which are curved in opposite directions in a radially three-dimensional manner and are fixed on the inside to the cylindrical collecting vessel, which is fixed to the cylindrical housing and has an annular opening in the direction of the counterflow blower.
The collecting vessel is of helical configuration and has a nozzle-shaped outlet opening, the helix being designed so as to descend in the direction of this outlet opening.
Apart from the quite complicated type of construction of a combination of this type, the propagation of noise caused by the axial fans used in this arrangement is considerable or troublesome at the high speed necessary.